Electric lamp and discharge devices: systems – Periodic switch in the supply circuit – Silicon controlled rectifier ignition
Reexamination Certificate
2009-05-08
2011-11-08
Ismail, Shawki (Department: 2819)
Electric lamp and discharge devices: systems
Periodic switch in the supply circuit
Silicon controlled rectifier ignition
C315S2090SC, C315S291000, C315S299000, C315S260000, C323S223000, C323S231000, C323S232000
Reexamination Certificate
active
08053997
ABSTRACT:
A two-wire load control device, such as a dimmer, is operable to control the amount of power delivered to an electrical load, such as a magnetic low-voltage (MLV) load, and comprises a bidirectional semiconductor switch, a timing circuit, a trigger circuit having a variable voltage threshold, and a clamp circuit. When a timing voltage signal of the timing circuit exceeds an initial magnitude of the variable voltage threshold, the trigger circuit is operable to render the semiconductor switch conductive, reduce the timing voltage signal to a predetermined magnitude less than the initial magnitude, and to increase the variable voltage threshold to a second magnitude greater than the first magnitude. The clamp circuit limits the magnitude of the timing voltage signal to a clamp magnitude between the initial magnitude and the second magnitude, thereby preventing the timing voltage signal from exceeding the second magnitude. Accordingly, multiple attempted firings of the semiconductor switch are avoided, and the MLV dimmer is prevented from conducting asymmetric current when an MLV transformer of the MLV load is unloaded.
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Abstract of DE 3913932 from espace.net.
Ismail Shawki
Lutron Electronics Co. Inc.
Rose Mark E.
Smith Philip N.
Tran Thienvu
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